1. Field of the Invention
The invention relates to an arrangement for storing an information signal in a memory and retrieving the information signal from said memory, the arrangement including the memory, an input terminal for receiving the information signal, an output terminal for supplying a delayed version of the information signal, an input buffer memory, having an input coupled to the input terminal and an output coupled to an input of said memory, and an output buffer memory having an input coupled to the output of said memory and an output coupled to said output terminal.
2. Description of the Related Art
Published international patent application no. WO91/13695 discloses the temporary storage of a video signal in a memory. Using this known arrangement, an information signal can be stored in the memory and an information signal previously stored in said memory can be retrieved simultaneously from said memory. The memory can be in the form of an optical disk or a magnetic disk, such as a hard disk or a disk-array. The arrangement can be used in a television apparatus or a videorecorder so as to store a video signal in the memory.
One application of the arrangement is where live television signal transmissions are continuously recorded and a history is maintained as far back as the extent of the memory will permit. For some applications, the memory capacity of the memory can be such that it permits the storage of a video signal having a length of a few minutes. For other applications a memory capacity corresponding to a length of about 15 minutes is considered a minimum practical amount.
The arrangement offers a number of interesting features to a user.
Individual choice of the time at which a program is watched. For example, suppose at ten past eight the viewer wants to start watching the eight o'clock news (from the beginning, of course). Using the arrangement, provided the right channel has been monitored, the viewer jumps back ten minutes in time, as it were, and watches the news from the start. Unlike the case where the program is recorded on a conventional video recorder, the viewer does not have to wait until the program has finished before watching it.
Continuity after an interruption. If the viewer is interrupted while watching a program, for example by a telephone call or a call at the door, he can resume watching the program from the point at which he was interrupted. This functionality is not possible with a conventional video-recorder.
A practical solution to program overlap. Suppose a program on one channel doesn't finish until ten minutes after the start of a program on another channel. The invention permits one to watch both programs without the use of a video recorder. During the first program, the viewer ensures that the channel of the second program is being monitored. After the first program has ended, the viewer switches to the other channel and jumps back to the start of the program. An important advantage over using a video recorder is that one does not have to wait until the recording has finished before the program can be watched.
Individual replays, including slow motion. The viewer can see a replay of an event just seen, (or just missed, or not fully understood) and then continue watching the program from the point where the replay was started. Moreover, the replays can be watched in slow motion.
Belated decision to record on video recorder possible. A viewer may decide after watching a program for ten minutes that the program is worth recording onto video tape. With the arrangement, he can retrospectively start video-recording, while continuing to watch the program live.
Additional features of the arrangement are:
A means of accelerating the viewing of a historical program. If the viewer is not watching live, e.g. due to a later program start or an interruption, he can catch up with the live broadcast by accelerating the playback. An acceleration factor of a few per cent is practically unnoticed by the viewer. The circuitry (disk readout, demultiplexing, data decompression, d/a conversion etc.) must be capable of processing the data at the accelerated rate. The sound can be specially processed so that the speed is accelerated without an undue increase in tone.
A means of fast-accelerating over a historical program. In this case not all television picture data is necessarily processed--some may be skipped and not be passed on for demultiplexing and decompression.
A fast reverse function.
A picture-in-picture (PIP) processing unit to enable combinations of live and historical programs to be displayed using picture-in-picture formats.
In order to enable an uninterrupted storage of a live television program in the main memory, and enable an uninterrupted and simultaneous retrieval of the historical program from the main memory, an input buffer memory and an output buffer memory are present. Data arriving for storage in the main memory, while the main memory is temporarily busy for another operation, will be stored in the input buffer memory, and will be stored at a later moment in the main memory by retrieving the data from the input buffer memory. Data will also be requested regularly from the main memory to be displayed on a TV screen as a historical program. Again, the main memory may be temporarily busy for another operation, so data must be readily available in the output buffer memory, so as to provide continuity of viewing for the user.